返回数组索引，其中subscore.js的子值最大

Question

I have a setup like this:

docs[0]['edits'] = 1;
docs[1]['edits'] = 2;

I want to get the docs[index] of the one with the most edits.

Using Underscore I can get the appropriate array (ie the value docs[1] ), but I still don't know the actual index in relation to docs .

_.max(docs, function(doc) { return doc['edits']; });

Any help would be greatly appreciated.

Answer 1

To do it without a library, iterate over the array (possibly with reduce ), storing the highest number so far and the highest index so far in a variable, reassigning both when the item being iterated over is higher:

 const edits = [ 3, 4, 5, 0, 0 ]; let highestNum = edits[0]; const highestIndex = edits.reduce((highestIndexSoFar, num, i) => { if (num > highestNum) { highestNum = num; return i; } return highestIndexSoFar; }, 0); console.log(highestIndex); 

Another way, with findIndex , and spreading the edits into Math.max (less code, but requires iterating twice):

 const edits = [ 3, 4, 5, 0, 0 ]; const highest = Math.max(...edits); const highestIndex = edits.indexOf(highest); console.log(highestIndex); 

Answer 2

Just use maxBy

const _ = require('lodash');

const docs = [{'edits': 1}, {'edits': 2}, {'edits': 0}, {'edits': 4}, {'edits': 3}]

const result = _.maxBy(docs, a => a.edits)

console.log(result)

https://repl.it/@NickMasters/DigitalUtterTechnologies

Pure JS way

const result2 = docs.reduce((result, { edits }) => edits > result ? edits : result, Number.MIN_SAFE_INTEGER)

console.log(result2)